Sytem and method for liquefying a fluid and storing the liquefied fluid

ABSTRACT

A Dewar system is configured to liquefy a flow of fluid, and to store the liquefied fluid. The Dewar system is disposed within a single, portable housing. Disposing the components of the Dewar system within the single housing enables liquefied fluid to be transferred between a heat exchange assembly configured to liquefy fluid and a storage assembly configured to store liquefied fluid in an enhanced manner. In one embodiment, the flow of fluid liquefied and stored by the Dewar system is oxygen (e.g., purified oxygen), nitrogen, and/or some other fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the priority benefit under 35 U.S.C. §371of international patent application no. PCT/IB2010/053888, filed Aug.30, 2010, which claims the priority benefit under 35 U.S.C. §119(e) ofU.S. Provisional Application No. 61/246,558 filed on Sep. 29, 2009, thecontents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the liquefaction of a fluid, and to storage ofthe liquefied fluid. In particular, the invention relates to systemsthat provide for liquefaction and storage in a unified and integratedmanner.

2. Description of the Related Art

Systems configured to liquefy fluids such as oxygen, nitrogen, and/orother fluids by reducing the temperature and increasing the pressure ofthe fluid being liquefied are known. Similarly, systems configured tostore liquefied fluids are known. However, these systems are generallyconfigured as separate solutions to separate problems. Consequently,conventional apparatus that have been configured to separately liquefyand store fluids rely on a transfer of fluid from a liquefaction systemto a storage system that is inefficient, and is prone to malfunction andfailure. Further, implementation of separate systems for liquefactionand storage may inhibit the portability, affordability, and/or usabilityof such conventional solutions.

SUMMARY OF THE INVENTION

One aspect of this invention relates to a system configured to liquefy afluid, and to store the liquefied fluid. In one embodiment, the systemcomprises a housing, a heat exchange assembly, and a fluid storageassembly. The housing is configured to substantially seal the interiorof the housing from atmosphere. The heat exchange assembly is disposedwithin the housing. The heat exchange assembly comprises a fluid conduitthat passes from inside the housing to outside the housing, and isconfigured to receive a flow of fluid in its gaseous state from a fluidflow generator located outside the housing. The heat exchange assemblyis configured to liquefy the flow of fluid received into the heatexchange assembly via the fluid conduit. The fluid storage assembly isdisposed within the housing. The fluid storage assembly is in fluidcommunication with the heat exchange assembly, and is configured tostore fluid that has been liquefied by the heat exchange assembly.

Another aspect of the invention relates to a method of liquefying afluid, and storing the liquefied fluid. In one embodiment, the methodcomprises substantially sealing a cavity from atmosphere; receiving aflow of fluid in a gaseous state into the cavity from outside the cavitythrough a fluid conduit, wherein the flow of fluid is received into thecavity in a gaseous state; liquefying the flow of fluid received intothe cavity via the fluid conduit; directing the liquefied fluid into areservoir disposed within the cavity; and storing the liquefied fluidwithin the reservoir.

Yet another aspect of the invention relates to a system configured toliquefy a fluid, and to store the liquefied fluid. In one embodiment,the system comprises means for substantially sealing a cavity fromatmosphere; means for receiving a flow of fluid in a gaseous state intothe cavity from outside the cavity, wherein the flow of fluid isreceived into the cavity by the means for receiving in a gaseous state;means for liquefying the flow of fluid received into the cavity, whereinthe means for liquefying the flow of fluid is disposed within thecavity; and means storing the liquefied fluid within the cavity.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. In one embodiment of the invention, the structuralcomponents illustrated herein are drawn in proportion. It is to beexpressly understood, however, that the drawings are for the purpose ofillustration and description only and are not a limitation of theinvention. In addition, it should be appreciated that structuralfeatures shown or described in any one embodiment herein can be used inother embodiments as well. It is to be expressly understood, however,that the drawings are for the purpose of illustration and descriptiononly and are not intended as a definition of the limits of theinvention. As used in the specification and in the claims, the singularform of “a”, “an”, and “the” include plural referents unless the contextclearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 2 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 3 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 4 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 5 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 6 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 7 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 8 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 9 illustrates a Dewar system configured to liquefy a flow of fluid,and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 10 illustrates a seal implemented within a Dewar system to seal aninterface assembly from a storage assembly, according to one or moreembodiments of the invention;

FIG. 11 illustrates a a heat exchange assembly and an interface assemblyin a Dewar system configured to liquefy a flow of fluid, and to storethe liquefied fluid, according to one or more embodiments of theinvention;

FIG. 12 illustrates a an interface assembly in a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, accordingto one or more embodiments of the invention;

FIG. 13 illustrates a heat exchange assembly formed integrally orsecurely with a lid of a housing that houses a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, inaccordance with one or more embodiments of the invention;

FIG. 14 illustrates a Dewar system configured to liquefy a flow offluid, and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 15 illustrates a an interface assembly in a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, accordingto one or more embodiments of the invention;

FIG. 16 illustrates a cold head from a heat exchange assembly configuredto liquefy a fluid, in accordance with one or more embodiments of theinvention;

FIG. 17 illustrates a heat exchange assembly formed integrally orsecurely with a lid of a housing that houses a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, inaccordance with one or more embodiments of the invention;

FIG. 18 illustrates a Dewar system configured to liquefy a flow offluid, and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 19 illustrates a a heat exchange assembly and an interface assemblyin a Dewar system configured to liquefy a flow of fluid, and to storethe liquefied fluid, according to one or more embodiments of theinvention;

FIG. 20 illustrates a a seal between an interface assembly and a heatexchange assembly in a Dewar system configured to liquefy a flow offluid, and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 21 illustrates a heat exchange assembly formed integrally orsecurely with a lid of a housing that houses a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, inaccordance with one or more embodiments of the invention;

FIG. 22 illustrates a Dewar system configured to liquefy a flow offluid, and to store the liquefied fluid, in accordance with one or moreembodiments of the invention;

FIG. 23 illustrates a Dewar system configured to liquefy a flow offluid, and to store the liquefied fluid, in accordance with one or moreembodiments of the invention; and

FIG. 24 illustrates an interface assembly in a Dewar system configuredto liquefy a flow of fluid, and to store the liquefied fluid, accordingto one or more embodiments of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1 and 2 illustrate a Dewar system 10 configured to liquefy a flowof fluid, and to store the liquefied fluid. The Dewar system 10 isdisposed within a single, portable housing 12. Disposing the componentsof Dewar system 10 within the single housing 12 enables liquefied fluidto be transferred between a heat exchange assembly 14 configured toliquefy fluid and a storage assembly 16 configured to store liquefiedfluid in an enhanced manner. For example, by virtue of enclosing heatexchange assembly 14 and storage assembly 16 within housing 12, thefluid is transferred between heat exchange assembly 14 and storageassembly 16 without implementing a conduit or line that must beindividually insulated against ambient atmosphere. As another example,the enclosure of heat exchange assembly 14 and storage assembly 16within housing 12 may enhance the portability and/or usability of Dewarsystem 10. In one embodiment, the flow of fluid liquefied and stored byDewar system 10 is oxygen (e.g., purified oxygen), nitrogen, and/or someother fluid.

Housing 12 is configured to substantially seal the interior of housing12 from atmosphere. As such, the interior of housing 12 forms a cavity18 that is substantially sealed from ambient atmosphere. This providessome isolation from ambient atmosphere for components of Dewar system 10that are disposed within cavity 18 of housing 12. To enhance thisisolation, housing 12 may be formed from an insulating material. By wayof non-limiting example, housing 12 may be formed from stainless steel,and/or other materials. To further insulate heat exchange assembly 14and storage assembly 16 from atmosphere, in one embodiment, housing 12may be evacuated between housing 12 and the portions of cavity 18 withinwhich heat exchange assembly 14 and/or storage assembly 16 are disposed.The created vacuum may provide an enhanced layer of insulation and/orprotection for heat exchange assembly 14 and/or storage assembly 16. Inaddition to providing insulation, housing 12 also provides structuralprotection for components disposed therein. As such, housing 12 is rigidto resist breakage caused by drops, collisions, and/or other forcesexperienced by Dewar system 10. Additionally, insulation wrap (notshown) may be used to coat the interior of housing 12 and/or componentcontained therein as an added one or more layers radiation barrier.

In one embodiment, housing 12 is formed from a first piece 20 and asecond piece 22. First piece 20 forms cavity 18 of housing 12 such thatcavity 18 has an opening formed by a rim 24. Second piece 22 is a lid,that is selectably coupled to first piece 20 at rim 24 of cavity 18 tosubstantially seal cavity 18 from atmosphere. The selectable couplingbetween first piece 20 and second piece 22 may be accomplished viareleasable fasteners 26 (e.g., bolts and nuts), as shown in FIGS. 1 and2. In other embodiments, alternative mechanisms for selectably couplingfirst piece 20 with second piece 22 may be implemented. For example,first piece 20 may be selectably coupled with second piece 22 viareleasable catches and/or latches, a threaded fit, a friction fit, apress fit, a snap fit, a detent mechanism, and/or other mechanisms forselectably coupling components. Although in the embodiment illustratedin FIGS. 1 and 2 first piece 20 and second piece 22 can be completelydecoupled from each other, this is not intended to be limiting. Instead,first piece 20 and second piece 22 may be coupled with each other in anon-removable manner at one or more locations. For example, first piece20 and second piece 22 may be coupled at one or more locations via hingesuch that first piece 20 can be second piece 22 partially decoupled andpivoted away from each other to expose cavity 18 of housing 12 toatmosphere. In one embodiment, first piece 20 and second piece 22 arecoupled in a non-removable manner (e.g., welded).

Heat exchange assembly 14 is configured to receive a flow of fluid in agaseous state, and to liquefy the received flow of fluid. Heat exchangeassembly 14 receives the flow of fluid from a source of fluid (notshown) that is external to housing 12. The source of fluid may include,for example, a fluid flow generator (e.g., a pressure swing adsorptiongenerator), a storage canister, a wall gas connection, and/or othersources of fluid.

Heat exchange assembly 14 is configured to liquefy the flow of fluid bylowering the temperature of the fluid. This may include supercooling thefluid down to temperatures of about 100° K or less at 1 atmosphere. Asis discussed below, in one embodiment, heat exchange assembly 14operates by circulation of compressor cooled refrigerant. However, thisis not intended to be limiting, and other types of heat exchange systemmay be disposed (in whole or in part) within housing 12 to liquefy theflow of fluid. For example, some other type of super-cooled fluid couldbe circulated within heat exchange assembly 14 rather than compressorcooled refrigerant (e.g., liquid nitrogen).

Storage assembly 16 is configured to store fluid that has been liquefiedby heat exchange assembly 14. In one embodiment, storage assembly 16includes a storage reservoir 28. Storage reservoir 28 is in fluidcommunication with heat exchange assembly 14 such that fluid that hasbeen liquefied by heat exchange assembly 14 is directed into storagereservoir 28. The liquefied fluid is then held within storage reservoir28 until it is needed. As the liquefied fluid is stored within storagereservoir 28, the temperature within storage reservoir 28 may rise tothe point where some of the fluid begins to boil off back into thegaseous state. At least some of this boiled off fluid may be vented fromhousing 12 to maintain the pressure within storage reservoir 28 at amanageable level.

In one embodiment, housing 12 is formed as a cylinder. This embodimentof housing 12 has a top 30 formed by second piece 22, and a bottom 32formed by first piece 20. When housing 12 is seated on bottom 32 in theembodiment shown in FIGS. 1 and 2, heat exchange assembly 14 and storageassembly 16 are disposed within housing 12 in a vertical configurationwith heat exchange assembly 14 positioned above storage assembly 16.

In one embodiment, storage assembly 16 is formed integrally or securelywith first piece 20. As used herein, the formation of storage assembly16 integrally or securely with first piece 20 refers to a constructionof storage assembly 16 and first piece 20 such that these two componentsare not intended to be separated during regular usage and/ormaintenance. While separation of storage assembly 16 and first piece 20may be achieved, reference to the secure and/or integral attachmentbetween these components reflects the relative strength and permanenceof this attachment during typical usage.

In one embodiment, heat exchange assembly 14 is formed integrally orsecurely with second piece 22. As used herein, the formation of heatexchange assembly 14 integrally or securely with second piece 22 refersto a construction of heat exchange assembly 14 and second piece 22 suchthat these two components are not intended to be separated duringregular usage and/or maintenance. While separation of heat exchangeassembly 14 and second piece 22 may be achieved, reference to the secureand/or integral attachment between these components reflects therelative strength and permanence of this attachment during typicalusage.

By virtue of the integral and secure formations of storage assembly 16with first piece 20 and of heat exchange assembly 14 with second piece22 in the embodiment illustrated in FIGS. 1 and 2, decoupling firstpiece 20 and second piece 22, and removing second piece 22 from firstpiece 20 results in heat exchange assembly 14 being withdrawn fromcavity 18 of housing 12. However, this decoupling leaves storageassembly 16 within cavity 18. As such, an interface assembly 34 thatplaces heat exchange assembly 14 in fluid communication with storageassembly 16 enables heat exchange assembly 14 to be selectably releasedfrom fluid communication storage assembly 16 when second piece 22 ofhousing 12 is decoupled from first piece 20 of housing 12.

FIGS. 3 and 4 illustrate one or more embodiments of Dewar system 10 inwhich when housing 12 is seated on bottom 32, heat exchange assembly 14and storage assembly 16 are located side by side within housing 12(rather than one on top of the other). In the one or more embodimentsdepicted in FIGS. 3 and 4, second piece 22 of housing 12 is disposedover heat exchange assembly 14 so that heat exchange assembly 14 can beformed integrally and securely with heat exchange assembly 14.

In the view of Dewar system 10 shown in FIG. 4, a fluid outlet 36provides selective fluid communication between storage assembly 16 andthe exterior of housing 12. Fluid outlet 36 enables fluid stored withinstorage assembly 16 to be released from storage reservoir 28 forpressure maintenance within storage reservoir 28 and/or for use. Fluidoutlet 36 includes an outlet conduit 38 and an outlet valve 40. Outletconduit 38 conveys fluid from within storage reservoir 28 to theexterior of housing 12. Outlet valve 40 is configured to selectably sealthe outlet conduit 38 such that the fluid from storage reservoir 28 canbe released from storage reservoir 28 in a controllable manner. In oneembodiment, rather than outlet valve 40, fluid outlet 36 may include aninterface (e.g., a threaded component, a component with a detentmechanism, etc.) that enables interface assembly 34 to be securelyinterfaced with a valve assembly that controls the release of fluid fromstorage reservoir 28. Fluid outlet 36 may be configured to release fluidfrom storage reservoir 28 in the gaseous state (e.g., for pressuremaintenance) and/or in the liquid state (e.g., for use).

FIGS. 5 and 6 illustrate one or more embodiments of Dewar system 10. Inthe embodiments illustrated in FIGS. 5 and 6, second piece 22 is notformed as a substantially flat lid that is selectably coupled to rim 24of first piece 20. Instead, second piece 22 itself forms a portion ofcavity 18 of housing 12. As can be seen in FIGS. 5 and 6, heat exchangeassembly 14 is nested inside of the portion of cavity 18 formed bysecond piece 22, while storage assembly 16 is nested inside of theportion of cavity 18 formed by first piece 20.

In one embodiment, a gasket 42 is disposed between first piece 20 andsecond piece 22. One or more openings 44 are formed in gasket 42.Through the one or more openings 44, the components of Dewar system 10housed within housing 12 communicate with the exterior of housing 12.For example, fluid from a fluid source may be communicated to heatexchange assembly 14 through an opening 44, fluid stored within storagereservoir 28 may be communicated to the exterior of the housing throughan opening 44, and/or other components of Dewar system 10 within housing12 may be communicated with the exterior of housing 12 through the oneor more openings 44.

FIGS. 7 and 8 illustrate one or more embodiments of Dewar system 10. Inthe embodiments illustrated in FIGS. 7 and 8, storage assembly 16 isdisposed within heat exchange assembly 14. In the depiction of Dewarsystem 10 shown in FIGS. 7 and 8, storage assembly 16 is shown as beingpositioned entirely within heat exchange assembly 14. This is notintended to be limiting. In one embodiment, heat exchange assembly 14only partially surrounds storage assembly 16.

FIGS. 9-13 illustrate one or more embodiments of Dewar system 10 inwhich heat exchange assembly 14 is positioned on top of storage assembly16 in the manner shown in FIGS. 1 and 2. Turning specifically to FIG. 9,heat exchange assembly 14 is shown as being encased by a heat exchangehousing 46 disposed within housing 12. Housing 46 houses heat exchangeassembly 14 within cavity 18. Housing 46 provides another layer ofinsulation between heat exchange assembly 14 and ambient atmosphere, andcreates a pocket of gas (or of vacuum) between housing 12 and housing 46that further insulates heat exchange assembly 14.

In one embodiment, heat exchange assembly 14 includes a refrigerantconduit 48. Refrigerant conduit 48 passes through housing 12 (e.g., atsecond piece 22) to communicate heat exchange assembly 14 with theexterior of housing 12. Refrigerant conduit 48 is configured to receiveand circulate a flow of cooled refrigerant. The flow of cooledrefrigerant may be received, for example, from a compressor (not shown)that cools the refrigerant, and is located outside of housing 12. Uponpassing through the length of refrigerant conduit 48, the refrigerantmay be conveyed out of housing 12 by refrigerant conduit 48 (e.g., backto the compressor for further cooling and re-circulation). In oneembodiment, refrigerant conduit 48 may be arranged in a coil, or someother labyrinthine configuration designed to minimize the volume of heatexchange assembly 14 as a whole while increasing the length ofrefrigerant conduit 48 included therein.

As can be seen in FIG. 9, in one embodiment, heat exchange assembly 14includes a fluid conduit 50 disposed in thermal communication with heatexchange assembly 14. In one embodiment, fluid conduit 50 is disposednext to and/or in contact with refrigerant conduit 48 such thatrefrigerant conduit 48 forms a heat sink along the length of fluidconduit 50. Fluid conduit 50 passes through housing 12 (e.g., at secondpiece 22) to communicate with the exterior of housing 12. The fluidconduit is configured to receive a flow of fluid in a gaseous state froma fluid source. The received flow of fluid is directed through fluidconduit 50. As the flow of fluid passes through fluid conduit 50, heatis removed from the fluid by refrigerant conduit 48. This reduces thetemperature of the flow of fluid to the point that the fluid istransformed from the gaseous state to a liquid state. The removal ofheat from the fluid within fluid conduit 50 may reduce the temperatureof the flow of fluid to a super-cooled level.

In one embodiment, heat exchange assembly 14 includes a cold head 52.

After directing the flow of fluid along the length of 48, fluid conduit50 may provide the flow of fluid into cold head 52. Cold head 52 isconfigured to further reduce the temperature of the flow of fluid suchthat any fluid not liquefied within fluid conduit 50 is liquefied incold head 52. In one embodiment illustrated in FIG. 9, cold head 52includes a secondary refrigerant conduit 54 and a condensing chamber 56.

Secondary refrigerant conduit 54 is configured to receive cooledrefrigerant (e.g., from refrigerant conduit 48, from an external source,etc.), and to circulate the refrigerant. Secondary refrigerant conduit54 is in thermal communication with cold head 52. In one embodiment,secondary refrigerant conduit 54 is disposed around the outside of coldhead 52 to provide a heat sink for cold head 52.

Condensing chamber 56 is formed by the body of cold head 52. Thecondensing chamber includes a fluid inlet 58 and a fluid outlet 60.Fluid inlet 58 communicates with fluid conduit 50 to receive cooled andat least partially liquefied fluid therefrom. Fluid outlet 60communicates with storage reservoir 28 to provide liquefied fluidthereto for storage. In one embodiment, one or more coalescingstructures 62 are formed within condensing chamber 56. Coalescingstructures 62 are configured to form super-cooled surfaces on whichfluid that has not yet been liquefied can be condensed. Coalescingstructures 62 are cooled by the heat sink provided to cold head 52 bysecondary refrigerant conduit 54. In one embodiment, condensing chamber56 is formed from a thermally conductive material, such as copper,aluminum, or other materials, that enhance the removal of heat fromcoalescing structures 62 by secondary refrigerant conduit 54.

During operation, fluid that is at least partially liquefied isintroduced into cold head 52 through fluid inlet 58, and migrates towardfluid outlet 60. As the fluid passes through condensing chamber 56 fromfluid inlet 58 to fluid outlet 60, fluid that has not been liquefiedbecomes condensed on coalescing structures 62. Thus, fluid provided tostorage reservoir 28 for storage and/or usage from cold head 52 issubstantially completely liquefied.

FIG. 9 further illustrates a transfill tube 64, and a fluid vent 66.Transfill tube 64 is configured to communicate liquefied fluid instorage reservoir 28 with the exterior of housing 12 (e.g., for usage).Fluid vent 66 is configured to enable fluid stored within storagereservoir 28 to be vented. For example, elevated pressures withinstorage reservoir 28 caused by liquefied fluid stored in storagereservoir 28 boiling off can be regulated by selectively venting fluidin the gaseous state (after boil-off) from storage reservoir 28 throughfluid vent 66.

As can be seen in FIG. 9, in one embodiment, interface assembly 34includes a reservoir neck 68 and a reservoir lid 70. Reservoir neck 68is provided at an opening in storage reservoir 28 of storage assembly 16that faces toward heat exchange assembly 14. Reservoir neck 68 has agenerally cylindrical shape. When Dewar system 10 is assembled andoperational, reservoir neck 68 is removably seated in an opening 72formed in housing 46 at an end of reservoir neck 68 opposite fromstorage reservoir 28. In one embodiment illustrated in FIG. 9, cold head52 is configured to be disposed inside of reservoir neck 68 when Dewarsystem 10 is assembled and operational.

Reservoir lid 70 is configured to fill the opening in storage reservoir28 by reservoir neck 68, thereby enclosing storage reservoir 28. In oneembodiment, reservoir lid 70 seals storage reservoir 28. For example,FIG. 10 provides a magnified view of a seal 74 that is carried byreservoir lid 70. Seal 74 includes an o-ring 76 and a spring backer 78that retains o-ring 76 in place on reservoir lid 70. When Dewar system10 is assembled and operational, o-ring 76 contacts a lip 80 formed atthe opening of storage reservoir 28 to seal storage reservoir 28.

FIGS. 11 and 12 provide magnified views of heat exchange assembly 14 andinterface assembly 34 together, and interface assembly 34 alone,respectively. As can be seen in these magnified views, in oneembodiment, coalescing structures 62 formed within cold head 52 includea plurality of screen meshes 82 separated by spacers 84. Screen meshes82 and/or spacers 84 may be formed from thermally conductive materials,such as copper, aluminum, or other materials, to enhance the removal ofheat from coalescing structures 62 by secondary refrigerant conduit 54through thermal conduction.

FIG. 13 provides a view of at heat exchange assembly 14 integrally orsecurely formed with second piece 22. Specifically, in the view shown inFIG. 13, decoupling second piece 22 from first piece 20 to open housing12 has resulted in heat exchange assembly 14 being removed from housing12. As can be seen in FIG. 13, in addition to heat exchange assembly 14,in one embodiment second piece 22 carries at least a portion ofinterface assembly 34 (e.g., lip 80).

FIGS. 14-17 illustrate one or more embodiments of Dewar system 10 inwhich heat exchange assembly 14 is positioned on top of storage assembly16 in the manner shown in FIGS. 1 and 2. In the one or more embodimentsillustrated in FIGS. 14-17, heat exchange assembly 14 does not include asecondary refrigerant conduit or condensing chamber. Instead, fluidexpelled from fluid conduit 50 is provided into a chamber formed byreservoir neck 68. As can be seen, for example, in the magnified view ofFIG. 15, cold head 52 is also disposed in this chamber.

Cold head 52 is formed having a cross-section that tends to enhance theamount of surface area on cold head 52. As fluid enters the chamberformed by reservoir neck 68 from fluid conduit 50, fluid that is stillin the gaseous state comes into contact with cold head 52. This causesthe fluid to condense, and then to flow down into storage reservoir 28for storage.

As can be seen in FIG. 15, the chamber within reservoir neck 68 isformed in part by a lid 86. Although lid 86 cooperates with reservoirneck 68 to form the chamber, lid 86 does not seal the chamber from heatexchange assembly 14. Instead, fluid within storage reservoir 28 in thegaseous state may escape from storage reservoir 28 into heat exchangeassembly 14 through and/or around lid 86. For example, the engagementbetween lid 86 and reservoir neck 68 may not be sealed, and/or lid 86may form a vent opening 88 shown in FIG. 16. Returning to FIG. 14, fluidthat escapes from storage reservoir 28 in the gaseous state into heatexchange assembly 14 may be released from housing 12 (e.g., toatmosphere) through a fluid outlet 90.

FIG. 17 provides a view of heat exchange assembly 14 and a portion ofinterface assembly 34 (e.g., lid 86) detached from the rest of Dewarsystem 10 by virtue of its integral and/or secure formation with secondpiece 22. As can be seen in FIG. 17, in one embodiment illustrated inFIGS. 14-17, decoupling second piece 22 from first piece 20 enables heatexchange assembly 14 (complete with cold head 52) and lid 86 to beremoved from cavity 18 of housing 12.

FIGS. 18-21 illustrate one or more embodiments of Dewar system 10 inwhich heat exchange assembly 14 is positioned on top of storage assembly16 in the manner shown in FIGS. 1 and 2. In one embodiment illustratedin FIGS. 18-21, cold head 52 is not located within reservoir neck 68,but instead is positioned within housing 46 with the rest of heatexchange assembly 14.

As can be seen in particular in FIGS. 19 and 20, interface assembly 34includes a lid 92 that seals reservoir neck 68 and storage reservoir 28from housing 46. As is shown in FIG. 21, when second piece 22 of housing12 is decoupled from first piece 20 of housing 12, lid 92 is removedfrom cavity 18 with heat exchange assembly 14.

FIG. 22 illustrates one or more embodiments of Dewar system 10 in whichheat exchange assembly 14 is positioned on top of storage assembly 16 inthe manner shown in FIGS. 1 and 2. However, in one embodimentillustrated in FIG. 22, reservoir neck 68 extends all the way throughhousing 12 from storage reservoir 28 to the opening in cavity 18, and isconfigured to engage second piece 22 of housing 12 when Dewar system 10is fully assembled. As such, if the interior of housing 12 is pumpeddown to form a vacuum therein, the vacuum space surrounds storagereservoir 28 and reservoir neck 68.

In one embodiment illustrated in FIG. 22, heat exchange assembly 14 isnot housed by housing 46, but instead is configured to surround at leasta portion of reservoir neck 68 in the vacuum space inside of housing 12.For example, refrigerant conduit 48, and fluid conduit 50 may be coiledabout reservoir neck 68 in the vacuum space formed within housing 12. Insome implementations, fluid conduit 50 may be wrapped around refrigerantconduit 48. This may enhance the amount of heat that is removed fromfluid within fluid conduit 50 by refrigerant flowing through refrigerantconduit 48.

In one embodiment illustrated in FIG. 22, heat exchange assembly 14 isformed integrally and/or securely within second piece 22 of housing 12.As such, if housing 12 is disassembled by removing second piece 22 fromfirst piece 20, heat exchange assembly 14 will be withdrawn from cavity18. However, this is not intended to be limiting, and in one embodiment,heat exchange assembly 14 is formed integrally or securely with firstpiece 20 of housing 12 such that if second piece 22 is removed fromfirst piece 20, heat exchange assembly 14 remains seated within cavity18.

FIGS. 23 and 24 illustrate one or more embodiments of Dewar system 10 inwhich heat exchange assembly 14 and storage assembly 16 are positionedside by side within housing 12 in the manner shown in FIGS. 3 and 4. Inone embodiment, fluid is received into heat exchange assembly 14 byfluid conduit 50, and heat is removed from the fluid within fluidconduit 50 in much the same manner as was described above with respectto FIGS. 9-13. The fluid is then dispensed into cold head 52, whichitself is disposed in housing 46 with the rest of heat exchange assembly14.

In one embodiment illustrated in FIGS. 23 and 24, upon being liquefiedby heat exchange assembly 14, fluid is provided to storage reservoir 28from cold head 52 by interface assembly 34. In this embodiment,interface assembly 34 includes a siphon conduit 94 that communicatescold head 52 with storage reservoir 28. The siphon conduit 94 may beformed with a releasable two-piece construction such that heat exchangeassembly 14 can be selectively decoupled from storage assembly 16 forremoval from housing 12. Or, siphon conduit 94 may be formed as asingle, or at least substantially non-releasable, conduit that runs froman outlet of cold head 52 to an inlet of storage reservoir 28.

As can be seen in particular in the magnified view of FIG. 24, betweenhousing 46 and storage reservoir 28, the thickness of the materialforming siphon conduit 94 may be greater than the thickness of thematerial within heat exchange assembly 14. This may insulate the flowpath formed by siphon conduit 94, and/or may enable siphon conduit 94 tomaintain its structural integrity in an embodiment in which the interiorof housing 12 is under vacuum.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. For example, it is to be understood thatthe present invention contemplates that, to the extent possible, one ormore features of any embodiment can be combined with one or morefeatures of any other embodiment.

1. A system configured to liquefy a fluid, and to store the liquefiedfluid, the system comprising: a housing configured to substantially sealthe interior of the housing from atmosphere; a heat exchange assemblydisposed within the housing, the heat exchange assembly comprising afluid conduit that passes from inside the housing to outside thehousing, the fluid conduit being configured to receive a flow of fluidin its gaseous state from a fluid flow generator located outside thehousing, the heat exchange assembly being configured to liquefy the flowof fluid received into the heat exchange assembly via the fluid conduit;and a fluid storage assembly disposed within the housing, the fluidstorage assembly being in fluid communication with the heat exchangeassembly, the fluid storage assembly being configured to store fluidthat has been liquefied by the heat exchange assembly.
 2. The system ofclaim 1, wherein the housing comprises a first piece and a second piece,wherein the first piece and the second piece are configured to beselectably coupled together to substantially seal the interior of thehousing from atmosphere, wherein the heat exchange assembly is formedintegrally or securely with the first piece of the housing, and whereinthe fluid storage assembly is formed integrally or securely with thesecond piece of the housing.
 3. The system of claim 2, wherein thesecond piece of the housing forms a cavity having an opening formed by arim of the second piece of the housing, and wherein the first piece ofthe housing is a lid that is selectably coupled to the rim of the secondpiece of the housing to substantially seal the cavity formed by thefirst piece of the housing from atmosphere.
 4. The system of claim 1,wherein the storage assembly comprises a reservoir neck that extendsfrom a storage reservoir to the housing enable liquefied fluid to bereleased from the storage reservoir, wherein a vacuum space is formedbetween the housing and the storage assembly, and wherein the heatexchange assembly is disposed in the vacuum space.
 5. The system ofclaim 1, wherein the fluid is oxygen.
 6. A method of liquefying a fluid,and storing the liquefied fluid, the method comprising: substantiallysealing a cavity from atmosphere; receiving a flow of fluid in a gaseousstate into the cavity from outside the cavity through a fluid conduit,wherein the flow of fluid is received into the cavity in a gaseousstate; liquefying the flow of fluid received into the cavity via thefluid conduit; directing the liquefied fluid into a reservoir disposedwithin the cavity; and storing the liquefied fluid within the reservoir.7. The method of claim 6, wherein substantially sealing the cavity fromatmosphere is performed by a first piece of a housing selectably coupledto a second piece of the housing to substantially seal the cavity, whichis formed in the interior of the housing, from atmosphere, wherein aheat exchange assembly that performs the liquefaction of the flow offluid is formed integrally or securely with the first piece of thehousing, and wherein the reservoir is formed integrally or securely withthe second piece of the housing.
 8. The method of claim 7, wherein thesecond piece of the housing forms the cavity such that the cavity has anopening formed by a rim of the second piece of the housing, and whereinthe first piece of the housing is a lid formed such that selectablycoupling the lid to the rim of the second piece of the housingsubstantially seals the cavity formed by the first piece of the housingfrom atmosphere.
 9. The method of claim 6, wherein a heat exchangeassembly that performs the liquefaction of the flow of fluid is disposedwithin a portion of the cavity this is under vacuum, and is external tothe reservoir.
 10. The method of claim 6, wherein the fluid is oxygen.11. A system configured to liquefy a fluid, and to store the liquefiedfluid, the system comprising: means for substantially sealing a cavityfrom atmosphere; means for receiving a flow of fluid in a gaseous stateinto the cavity from outside the cavity, wherein the flow of fluid isreceived into the cavity by the means for receiving in a gaseous state;means for liquefying the flow of fluid received into the cavity, whereinthe means for liquefying the flow of fluid is disposed within thecavity; means storing the liquefied fluid within the cavity.
 12. Thesystem of claim 11, wherein the means for sealing the cavity fromatmosphere comprises a first piece and a second piece, the first pieceand second piece being selectably coupled to seal the cavity fromatmosphere, wherein the means for liquefying is formed integrally orsecurely with the first piece of the means for substantially sealing,and wherein the means for storing is formed integrally or securely withthe second piece of the means for substantially sealing.
 13. The systemof claim 12, wherein the second piece of the means for substantiallysealing forms the cavity such that the cavity has an opening formed by arim of the second piece of the means for substantially sealing, andwherein the first piece of the means for substantially sealing is a lidformed such that selectably coupling the lid to the rim of the secondpiece of the means for substantially sealing substantially seals thecavity from atmosphere.
 14. The system of claim 11, wherein the portionof the cavity that is external to the means for storing is under vacuum,thereby creating a vacuum space, and wherein the means for liquefying isdisposed in the vaccum space.
 15. The system of claim 11, wherein thefluid is oxygen.